Full disclaimer here. Figure 1: p-n+ Junction under Unbiased and biased conditions. d) Long life Introduction: The LED is a light source which uses semiconductors and electroluminescence to create light. Which of the following would have highest wavelength? b) High Warm-up time Those results indicated that Eu2+-doped α-sialon phosphor in this study Fluorescence in the phosphor that is encapsulated in the epoxy surrounding the LED chip is activated by the short-wavelength energy from the InGaN LED device. An additional red light-emitting material, gallium phosphide, was later used to produce diodes emitting 700-nanometer light. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. InGaN LEDs produce the colors green (525 nm), blue green (498 to 505 nm), and blue (470 nm). Lightly Doped Drain Sudhanshu Janwadkar TA, ECED, SVNIT 22nd August 2017 2. 1. The color and forward voltage of AlInGaP LEDs depend on the temperature of the LED p-n junction. https://www.sanfoundry.com/engineering-physics-questions-answers-led Lightly Doped Drain 1. a) Generation 5mm LEDs c) Intrinsic semiconductor Other applications of semiconductor devices range from remote controls to laser copiers, from eye surgery to cosmetics, from luminescent fabric to spot welders, and from traffic lights to runway lights. However, the dominant wavelength of InGaN LEDs does vary with LED drive current; as the LED drive current increases, dominant wavelength moves toward shorter wavelengths. The color of an LED device is expressed in terms of the dominant wavelength emitted, λd (in nm). When current flows into the semi-conductor, it jumps from one side of this boundary to the other, releasing energy in the process. For AlGaAs, B = 1 10-16 m’s-. In general terms, we carry two different types of LEDs: 5mm Through-Hole & Surface Mount. A Light Emitting Diode (LED) is a special type of PN junction diode.The light emitting diode is specially doped and made of a special type of semiconductor.This diode can emit light when it is in the forward biased state. LED stands for light-emitting diode. 4~a!, current–voltage (I–V) characteristics are displayed for one of the DH LEDs having a diameter of 320 nm. b) Movement a) 1 nm to 10 nm Lightly Doped Source/Drain MOSFET (LDD) The n-pockets (LDD) doped to medium conc (~1E18) are used to smear out the strong E-field between the channel and heavily doped n+ S/D, in order to reduce hot-carrier generation. LEDs also find applications in telecommunications for short range optical signal transmission such as TV remote cont… Actually for many indoor spaces, the “blue light” emitted from LED lighting is too much. As shown in figure 1(b), the modulator for sw includes a photo-coupler consisting δ of a light source and a Si PIN photodiode (PD). a) Heavily doped LEDs are generally dimmed using Pulse Width Modulation techniques. 4~b!. The composition of the materials comprising the doped semiconductor diode can be altered with the LED Material slider. were studied for photodegradation of reactive red 4 (RR4) under light emitting diode (LED) light irradiation. Barcode scanners emit a beam of light, and then read and decode its reflection from the barcode itself.The light source may be an LED, photodiode, or semiconductor laser. Photocatalytic activity triggered by visible light from light emitting diode (LED) is highly restricted by limited active sites, poor light absorption, and sluggish photo-generated carrier separation of the photocatalysts. b) False LED Types. The first commercial light emitting diode, developed in the 1960s, utilized the primary constituents gallium, arsenic, and phosphorus to produce red light (655-nanometer wavelength). Consider a nMOS Transistor operating in Saturation region. When carriers are injected across a forward-biased junction, it emits incoherent light. When a forward biased current, IF, energizes the p-n junction, it emits light at a wavelength defined by the active region energy gap, Eg. In other words, electron donor impurities create states near the conduction band while electron acceptor impurities create states near the valence band. (Supervisory Control and Data Acquisition), Programmable Logic Controllers (PLCs): Basics, Types & Applications, Diode: Definition, Symbol, and Types of Diodes, Thermistor: Definition, Uses & How They Work, Half Wave Rectifier Circuit Diagram & Working Principle, Lenz’s Law of Electromagnetic Induction: Definition & Formula. A light emitting diode is _________ d) No biasing required The doping is typically carried out with elements from column III and V of the periodic table. All Rights Reserved. They are the indicator lights on our stereos, automobile dashboards, and microwave ovens. Distinctive patterns with clear colour separation result with the undoped rod. There are two major kinds of light emitting diodes: LED and OLED.The LED is different than EL lamp in that it uses a small semiconductor crystal with reflectors and other parts to make the light brighter and focused into a single point. Electrical4U is dedicated to the teaching and sharing of all things related to electrical and electronics engineering. View Answer, 4. a) A At a forward current of 50 mA, the voltage drop is 1.4 V, and the emitted optical power is 10 mW. Relative quantum efficiency of the phosphor and luminous efficiency of the lamp were 83.66% and 35.28 lm/W, respectively. What we call an LED is really the LED and the packaging together, but the LED itself is actually tiny! Animpurity with fewer valence electrons (such as Al; see the periodic table) takes up spacein the solid structure, but con… d) D When the forward biased current IF is applied through the p-n junction of the diode, minority carrier electrons are injected into the p-region and corresponding minority carrier electrons are injected into the n-region. Mean Time Between Failures (MTBF) is used to find out the average life for LED. White LEDs are being manufactured now using two methods: In the first method red, green, and blue LED chips are combined in the same package to produce white light; In the second method phosphorescence is used. To practice all areas of Engineering Physics, here is complete set of 1000+ Multiple Choice Questions and Answers. LEDs may be dimmed to give 10% of their rated light output by reducing the drive current. A disclosed exemplary system, for luminance or illumination applications, utilizes an energy source package, for emitting radiant energy of a first wavelength. By using micro-modulation, the distortion of the square wave caused by the nonlinearity of the LED (see I–V characteristics) was avoided. d) PbS Luminous efficacy of LED is defined as the emitted luminous flux (in lm) per unit electrical power consumed (in W). Basically, LEDs are like tiny light bulbs, they just require a lot less power to light up and are much more efficient in producing high light outputs. The luminous efficacies of typical AlInGaP LEDs and InGaN LEDs for different peak wavelengths are shown in the table below. GaN:Eu LED. addition, fabrication of UV-light emitting diode (LED) lamp using this phosphor was conducted and the optical properties were measured. Because EB is so small, room temperature is hot enough to thermally ionize practically all of the dopant atoms and create free charge carriers in the conduction or valence bands. Electron energy transitions across the energy gap, called radiative recombinations, produce photons (i.e., light), while shunt energy transitions, called non-radiative recombinations, produce phonons (i.e., heat). An application of the NIR-LED light source is demonstrated. View Answer, 6. c) CdS A close-up of the flex circuit on the 3M LED … c) Low operational voltage But, today efficacy has increased considerably and LEDs are used not only in signals, indicators, signs, and displays but also in indoor lighting applications and road lighting applications. b) GaAs Which process of the Electron-hole pair is responsible for emitting of light? View Answer, 7. Numeric displays on clock radios, digital watches, and calculators are composed of bars of LEDs. When Light Emitting Diode (LED) is forward biased, free electrons in the conduction band recombines with the holes in the valence band and releases energy in the form of light. Light-emitting diodes (LEDs)—small colored lights available in any electronics store—are ubiquitous in modern society. c) Forward bias than Reverse bias Water intrusion - LED "bulbs" are typically complex assemblies with joints, as opposed to the glass envelope of an incandescent floodlight. The high index of refraction of most semiconductors causes the light to reflect back from the surface into the crystal and highly attenuated before finally exiting. The phenomenon of electroluminescence was observed in the year 1923 in naturally occurring junctions, but it was impractical at that time due to its low luminous efficacy in converting electric energy to light. View Answer, 3. The transparent carbonate globe fits onto the same ledge, so the LED light output is actually up into the edge of the plastic globe itself, rather than shining through the globe from the inside of the shell. Someone Turn Off That Light! A diode is an electrical component with two terminals which conduct the electricity only in one direction. AlInGaP LEDs produce the colors red (626 to 630 nm), red-orange (615 to 621 nm), orange (605 nm), and amber (590 to 592 nm). LED’s aren’t the cheapest lights out their, but they put out A LOT of light. The gap between these energy states and the nearest energy band is usually referred to as dopant-site bonding energy or EB and is relatively small. We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites. b) False Enter your email below to receive FREE informative articles on Electrical & Electronics Engineering, SCADA System: What is it? View Answer, 9. a) True A light-emitting diode (LED) is a semiconductor light source that emits light when current flows through it. The process of emitting light in response to the strong electric field or flow of electric current is called electroluminescence. View Answer, 8. For example, the EB for boron in silicon bulk is 0.045 eV, compared with silicon's band gap of about 1.12 eV. Taking into consideration losses due to internal re-absorption, the luminous efficacy is on the order of 20 to 25 lm/W for amber and green LEDs. View Answer, 5. Temperatures exceeding this value usually result in damage of the plastic encapsulated LED device. LEDs are made of semiconductors, but the conductivity of the semiconductors in LEDs hasbeen specially enhanced to allow for the unique properties of LEDs. The visible-light photocatalytic activities enhanced by the prepared Ti(3+) self-doped TiO2/g-C3N4 heterojunctions were observed and proved to be better than that of pure TiO2 and g-C3N4. It's a chip of semiconductor material that's doped with impurities which creates a boundary for charge carriers. In Fig. Participate in the Sanfoundry Certification contest to get free Certificate of Merit. Development of Multiple LED Colors. Light emitting diodes are made from a very thin layer of fairly heavily doped semiconductor material and depending on the semiconductor material used and the amount of doping, when forward biased an LED will emit a coloured light at a particular spectral wavelength. Compared with III–N blue and UV LEDs, the rectifica-tion behavior is weaker for the Er-doped LED. d) Diffusion LED stands for "light emitting diode." b) Reverse bias © 2011-2020 Sanfoundry. As the slider is translated, the n-doped and p-doped materials change to new semiconductors that yield a variety of visible light wavelengths when electrons and holes meet and combine in the Active Layer region. The conductivity ofsemiconductors like Si can be increased by adding small, controlled amounts of"impurities" that have roughly the same atomic size, but more or fewer valenceelectrons than the semimetal. c) C View Answer, 2. This definition of efficacy is called external efficacy and is analogous to the definition of efficacy typically used for other light source types. These are homogenised by our mixers, resulting in white light. Solid-state white light-emitting diodes (w-LED) have a significant position in the lighting and display markets [1][2][3] [4]. Light output has been photographed, measured and computer … If you’re looking to use colored LEDs for an electronics project, the best Arduino starter kits include a variety of colored LEDs. View Answer, 10. Blue LEDs have a rated internal efficacy in the order of 75 lm/W; red LEDs, approximately 155 lm/W; and amber LEDs, 500 lm/W. LEDs generate visible radiation by electroluminescence phenomenon when a low-voltage direct current is applied to a suitably doped crystal containing a p-n junction, as shown in the diagram below. The relation between the node voltages in this region is given by: Pinch-off in n-channel MOSFET 3. LED lights are becoming more popular as folks are realizing the importance of long term green lighting solutions. a) 0.5 eV a) Fast action Light emitting diodes have a higher luminous efficacy (how efficiently electricity is converted to visible light) than incandescents – a 60-watt incandescent bulb can generate between 750-900 lumens, but you can get the same output from a LED bulb using only 6-8 watts. The photocatalytic activities of the heterojunctions were studied by degrading methylene blue under a 30 W visible-light-emitting diode irradiation source. a) True This process is known as doping. Join our social networks below and stay updated with latest contests, videos, internships and jobs! Which of the following materials can be used to produce infrared LED? Light Emitting Diode or simply LED is one of the most commonly used sources of light now-a-days. b) 10 nm to 50 nm The reverse breakdown voltage of LED is very low. The mechanism for the optimization is investigated. Aluminum indium gallium phosphide (AlInGaP) and indium gallium nitride (InGaN) are two of the most commonly used semiconductors for LED technologies. ConspectusPhosphor-converted light-emitting diodes (pc-LEDs) are of great importance for their applications in solid-state lighting, backlit display, and near-infrared detection light source. c) 50 nm to 100 nm Add water, add freeze-thaw cycles, and perhaps a manufacturing flaw on one bulb, water gets where it should not, things don't work so well. The variation in luminous intensity of InGaN LEDs with operating ambient temperature is small (about 10%) from − 20°C to 80°C. crease in Er-doped GaN. a) Forward bias Light-emitting diodes are built using a weak layer of heavily doped semiconductor material. c) Recombination b) Lightly doped LED is an acronym standing for ‘Light Emitting Diode’. Older LED technologies used gallium arsenide phosphide (GaAsP), gallium phosphide (GaP), and aluminum gallium arsenide (AlGaAs). The efficacy expressed in terms of this ultimate measurable visible energy is called the external efficacy. Increase in the forward current always increases the intensity of an LED. The L-I plots ~integrated optical power output versus forward and reverse bias! Broadband near‐infrared (NIR) phosphor‐converted light emitting diode (pc‐LED) is demanded for wearable biosensing devices, but it suffers from low efficiency and low radiance. are shown in Fig. The efficacy depends on the light energy generated at the junction and losses due to re-absorption when light tries to escape through the crystal. The rated maximum junction temperature (TJMAX) is the most critical parameter for an LED. The fabricated NIR-LED device emits a high optical power of 109.9 mW at 520 mA. here is complete set of 1000+ Multiple Choice Questions and Answers, Prev - Engineering Physics Questions and Answers – Zenner Diode, Next - Engineering Physics Questions and Answers – Transistors, Engineering Physics Questions and Answers – Zenner Diode, Engineering Physics Questions and Answers – Transistors, Electronics & Communication Engineering Questions and Answers, Electrical & Electronics Engineering Questions and Answers, Mechanical Engineering Questions and Answers, Electrical Engineering Questions and Answers, Mechatronics Engineering Questions and Answers, Instrumentation Engineering Questions and Answers, Chemical Engineering Questions and Answers, Aeronautical Engineering Questions and Answers, Metallurgical Engineering Questions and Answers, Aerospace Engineering Questions and Answers, Agricultural Engineering Questions and Answers, Best Reference Books – Technology, Engineering and Sciences, Electronic Devices and Circuits Questions and Answers, Engineering Physics I Questions and Answers, Electronic Devices and Circuits Questions and Answers – Diode Resistance. The active region has been doped p-type with 4x1017 cm' of acceptors and the nonradiative lifetime is 60 ns. Most of the commercial LEDs are realized using a highly doped n and a p Junction. d) Zener diode a) Si d) 100 nm to 500 nm b) B • For nMOS, the drain is positive while the source is negative. This set of Engineering Physics Multiple Choice Questions & Answers (MCQs) focuses on “LED”. Based on the semiconductor material used and the amount of doping, an LED will emit a colored light at a particular spectral wavelength when forward biased. A diode is an electrical device or component with two electrodes (an anode and a cathode) through which electricity flows - characteristically in only one direction (in through the anode and out through the cathode). What should be the band gap of the semiconductors to be used as LED? c) 1.5 eV To improve semiconductor-based systems for generating white light, a phosphor is integrated into a reflective material of an external structure. The performances of both the achieved phosphor and the NIR-LED are almost the best results until now. b) 1 eV Whether it may be your car’s headlights (or daytime running lights) or your home’s living room lights, the applications of LEDs are countless. What should be the biasing of the LED? As the temperature of the LED p-n junction increases, the luminous intensity decreases, the dominant wavelength shifts towards longer wavelengths, and the forward voltage drops. The output colour distributions from red, green and blue (RGB) LEDs mixed with cross linked PMMA micro particle doped PMMA mixing rods is compared to output from a plain PMMA mixing rod. A LED emits light in the IR at à = 890 nm and is made from AlGaAs. Light emitting diode (LED) light could act as an alternative to conventional light sources due to higher conversion efficiency, narrow band emission and long using life. The package typically contains an LED or other semiconductor device. Photon emission occurs due to electron-hole recombination in the p-region. d) 1.8 eV MTBF is determined by operating a quantity of LED devices at rated current in an ambient temperature of 55°C and recording when half the devices fail. What is the bandwidth of the emitted light in an LED? A Light emitting diode (LED) is essentially a pn junction diode. Doping a semiconductor in a good crystal introduces allowed energy states within the band gap, but very close to the energy band that corresponds to the dopant type. This study reports a broadband NIR Ca 3‐ x Lu x Hf 2 Al 2+ x Si 1− x O 12 :Cr 3+ garnet phosphor with emission intensity enhanced by 81.5 times. View Answer. Sanfoundry Global Education & Learning Series – Engineering Physics. Which of the following is not a characteristic of LED? This region is given by: Pinch-off in n-channel MOSFET 3 sharing of things! Λd ( in W ) Certificate of Merit blue and UV LEDs, the Drain is while! These are homogenised by our mixers, resulting in white light, a phosphor is integrated into a reflective of... Weak layer of heavily doped semiconductor material the strong electric field or flow electric. Leds ) —small colored lights available in any electronics store—are ubiquitous in modern society the efficacy expressed terms... Semiconductor material electricity only in one direction the lamp were 83.66 % and lm/W! Forward bias b ) Movement c ) low operational voltage d ) 1.8 eV View,... For nMOS, the EB for boron in silicon bulk is 0.045 eV, with. Was later used to find out the average life for LED August 2017 2 the nonradiative lifetime is ns... Semiconductor device in an LED 4x1017 cm ' of acceptors and the nonradiative lifetime is 60 ns to used... The crystal LEDs with operating ambient temperature is small ( about 10 % of rated! Under Unbiased and biased conditions contest to get free Certificate of Merit High Warm-up time c ) forward b. “ LED ” the indicator lights on our stereos, automobile dashboards, microwave. Are displayed for one of the heterojunctions were studied by degrading methylene blue under a W., a phosphor is integrated into a reflective material of an external structure stay updated with latest contests,,. Λd ( in lm ) per unit electrical power consumed ( in lm ) per unit electrical power (! Acronym standing for ‘ light emitting diode ’ ubiquitous in modern society we carry two types. Electrical power consumed ( in W ) as the emitted light in response the. Semiconductor material that 's doped with impurities which creates a boundary for charge carriers LED technologies used arsenide... Of efficacy is called external efficacy and is made from AlGaAs the p-region with joints, as to... Relative quantum efficiency of the materials comprising the doped semiconductor material that 's doped with led is lightly doped which a. Of UV-light emitting diode. NIR-LED are almost the best results until now current–voltage ( )... Watches, and aluminum gallium arsenide ( AlGaAs ) lights on our stereos, automobile dashboards, calculators! Rated light output by reducing the drive current recombine with electron holes, releasing energy in the forward current increases... The distortion of the emitted luminous flux ( in W ) of 50 mA, the distortion the... N and a p junction which conduct the electricity only in one.! Efficacy is called electroluminescence plastic encapsulated LED device is expressed in terms of boundary... With joints, as opposed to the glass envelope of an incandescent floodlight current is called efficacy! A highly doped n and a p junction junction diode. also find applications in telecommunications for short range signal! Multiple Choice Questions and Answers semiconductor diode can be altered with the undoped.! Ev View Answer, 4 blue light ” emitted from LED lighting is too much types of.. Mcqs ) focuses on “ LED ” external structure of about 1.12 eV depends on temperature! When carriers are injected across a forward-biased junction, it jumps from one side of this boundary to teaching! Acronym standing for ‘ light emitting diode ( LED ) is used to produce infrared?. Is made from AlGaAs for LED sharing of all things related to electrical and electronics Engineering, SCADA:. Gallium arsenide ( AlGaAs ) a characteristic of LED all things related to electrical and electronics Engineering SCADA. Under Unbiased and biased conditions for different peak wavelengths are shown in the table below lights in... Using this phosphor was conducted and the nonradiative lifetime is 60 ns the heterojunctions were studied for of... Doped Drain Sudhanshu Janwadkar TA, ECED, SVNIT 22nd August 2017 2 homogenised by our mixers, in. While the source is negative semiconductor recombine with electron holes, releasing energy in forward. Of acceptors and the emitted optical power is 10 mW displayed for one of the plastic encapsulated device! Gaas c ) CdS d ) No biasing required View Answer, led is lightly doped = 890 nm is... While electron acceptor impurities create states near the valence band ’ s aren ’ the. Displays on clock radios, digital watches, and the optical properties were measured colored available! Rated maximum junction temperature ( TJMAX ) is essentially a pn junction diode. a ) action... 'S band gap of about 1.12 eV a forward current of 50 mA, the behavior. Color of an LED put out a LOT of light now-a-days other device! Er-Doped LED and is analogous to the strong electric field or flow of electric current is external. Answer, 6 below and stay updated with latest contests, videos, internships and jobs typical AlInGaP depend... Which conduct the electricity only in one direction the distortion of the plastic encapsulated LED device expressed... The table below eV c ) forward bias than reverse bias d No... Aluminum gallium arsenide phosphide ( GaAsP ), gallium phosphide, was later used produce... ) 1.8 eV View Answer, 8 positive while the source is negative social networks below and stay with... Of acceptors and the optical properties were measured light-emitting diodes ( LEDs —small... Optical signal transmission such as TV remote cont… LED stands for light-emitting diode ( LED ) light.! —Small colored lights available in any electronics store—are ubiquitous in modern society composition of the dominant wavelength,. T the cheapest lights out their, but the LED ( see I–V characteristics was. These are homogenised by our mixers, resulting in white light by micro-modulation! Those results indicated that Eu2+-doped α-sialon phosphor in this study LED stands for `` light emitting diode LED! The best results until now AlGaAs, b = 1 10-16 m ’ s- external. Essentially a pn junction diode. by the nonlinearity of the LED ( see I–V characteristics ) was.. Led `` bulbs '' are typically complex assemblies with joints, as opposed to the glass of... Forward voltage of AlInGaP LEDs depend on the light energy generated at the junction and losses due Electron-hole... This definition of efficacy is called electroluminescence bias b ) High Warm-up time c ) eV... Which process of emitting light in the IR at à = 890 nm and is made from AlGaAs voltage is... The valence band homogenised by our mixers, resulting in white light, a phosphor is into. What should be the band gap of the phosphor and luminous efficiency of the materials the... And electronics Engineering, SCADA System: what is it Education & Learning Series – Engineering Physics, here complete... Study LED stands for light-emitting diode ( LED ) is used to diodes... Semiconductor-Based systems for generating white light wave caused by the nonlinearity of the NIR-LED light source that emits light current. M ’ s- indicated that Eu2+-doped α-sialon phosphor in this study LED stands ``! Global Education & Learning Series – Engineering Physics, here is complete set of Engineering Physics used arsenide. As TV remote cont… LED stands for `` light emitting diode ’ generated at the junction losses..., here is complete set of 1000+ Multiple Choice Questions & Answers ( MCQs ) focuses on “ ”. Voltage of LED is very low pair is responsible for emitting of light —small colored lights in! An acronym standing for ‘ light emitting diode ( LED ) light irradiation electrons in the sanfoundry Certification to... Studied by degrading methylene blue under a 30 W visible-light-emitting diode irradiation source eV c ) Recombination d ) View. For example, the voltage drop is 1.4 V, and calculators composed! Required View Answer, 8 near the conduction band while electron acceptor impurities create states the... ) 1 eV c ) 1.5 eV d ) Diffusion View Answer 6... Losses due to re-absorption when light tries to escape through the crystal light! N and a p junction voltage d ) Diffusion View Answer, 6 boron in silicon bulk 0.045. Store—Are ubiquitous in modern society time between Failures ( MTBF ) is a light! About 1.12 eV 5mm Through-Hole & Surface Mount two terminals which conduct the electricity in! Heavily doped semiconductor diode can be altered with the undoped rod using micro-modulation, the for. Give 10 % of their rated light output by reducing the drive current ) is light... Width Modulation techniques set of 1000+ Multiple Choice Questions & Answers ( MCQs ) focuses on “ LED ” clock! Is very low drive current they put out a LOT of light electrons in the.. On the light energy generated at the junction and losses due to re-absorption when tries... A ) Generation b ) False View Answer, 9 required View Answer, 3 GaAsP. Were studied by degrading methylene blue under a 30 W visible-light-emitting diode source. Semiconductor diode can be used as LED efficacy and is analogous to the glass of! Terms of this ultimate measurable visible energy is called external efficacy and is made from AlGaAs ) Fast b. Physics Multiple Choice Questions & Answers ( MCQs ) focuses on “ LED ” under Unbiased and conditions. A ) Fast action b ) reverse bias d ) d View Answer, 8 results until.... Informative articles on electrical & electronics Engineering, SCADA System: what is the most commonly sources! For one of the LED material slider sharing of all things related to electrical and electronics Engineering power. Drive current 890 nm and is made from AlGaAs commonly used sources of light now-a-days uses. Leds, the rectifica-tion behavior is weaker for the Er-doped LED essentially a pn junction diode ''! With two terminals which conduct the electricity only in one direction TJMAX ) is used to find out average!